Form的OnMouseWheel事件
procedure TForm1.FormMouseWheel(Sender: TObject; Shift: TShiftState;
WheelDelta: Integer; MousePos: TPoint; var Handled: Boolean);
begin
Form1.VertScrollBar.Position:= Form1.VertScrollBar.Position- (WheelDelta div 20); // 数值越小,滚动越快。
end;